The present invention related to a cooling device and a projection display device. For example, the present invention relates to a cooling device that cools a light source of a projector and a projection display device.
Semiconductor light sources such as lasers and light emitting diodes (LEDs) have been increasingly used as light sources of projectors. Since a semiconductor light source has a high heat-generating density, it is cooled by using a radiator. Examples of disclosed cooling structures include a structure in which a radiator such as a heat sink is connected to a heat source and air is sent to the radiator, and a structure for cooling a light-source lamp by using a heat pipe.
Japanese Unexamined Patent Application Publication No. 2003-075081 discloses a projection display device 4 including a lamp 5, which is a heat source, a heat-receiving block 42 to which the heat source is connected, a heat sink 47 including a plurality of radiation fins 48 disposed therein, and an exhaust fan 49 for sending air to the heat sink 47 and thereby causing heat to radiate therefrom as shown in FIGS. 8A and 8B. The projection display device 4 disclosed in Japanese Unexamined Patent Application Publication No. 2003-075081 transfers heat generated in the heat source to the heat sink 47 through the heat-receiving block 42 and heat pipes 43, and causes the transferred heat to externally radiate from the heat sink 47 by using the exhaust fan 49.
Further, Japanese Unexamined Patent Application Publication No. 2009-238948 discloses a heat sink equipped with fins, including an axial fan with an air-inlet and an air-outlet formed therein, first radiation fins disposed in the air-inlet, second radiation fins disposed in the air-outlet, a heat pipe connecting the first radiation fins with the second radiation fins, and a heat-receiving block joined to the heat pipe. The heat sink equipped with fins transfers heat generated in a heat source to the first and second radiation fins through the heat pipe, and causes the transferred heat to externally radiate from the first and second radiation fins by using an exhaust fan 49.
It should be noted that when the size of radiation fins disposed in a heat sink and/or a heat pipe is increased to increase the cooling efficiency of the radiation fins, the radiation efficiency does not improve when the size of the radiation fins reaches a certain size and the radiation efficiency saturates there. Further, when the size of radiation fins is increased, their air resistance increases, thus causing a problem that even when the volume of air is increased, the radiation cannot be improved in accordance with the size of the radiation fins.
The present invention has been made to solve the above-described problem and an object thereof is to provide a cooling device and a projection display device capable of improving the cooling performance of a heat source.